Event to signal

Alexey Serebryakov

Hi guys,
i've try to use event to signal feature but take an errors.

Header-only feature class EventsToSignals.hpp:

#ifndef EVENTSTOSIGNALS_H
#define EVENTSTOSIGNALS_H
 
#include <QObject>
#include <QEvent>
 
class EventsToSignals : public QObject
{
    Q_OBJECT
    const QEvent::Type type;
public:
    explicit EventsToSignals(QObject*parent, QEvent::Type t = QEvent::None )
        : QObject(parent), type(t)
    {
        parent->installEventFilter(this);
    }
 
signals:
    void onEvent(QObject *watched, QEvent *event);
 
private:
    bool eventFilter(QObject *watched, QEvent *event)
    {
        bool handled = QObject::eventFilter(watched, event);
        if( type==QEvent::None || type==event->type() )
            emit onEvent(watched, event);
        return handled;
    }
};
 
template<typename ... Args >
auto connectEvent(QObject *obj, QEvent::Type t, Args ... args)
{
    return obj->connect( new EventsToSignals(obj, t), &EventsToSignals::onEvent, args... );
}
template<typename ... Args >
auto connectEvent(QObject *obj, Args ... args)
{
    return obj->connect( new EventsToSignals(obj), &EventsToSignals::onEvent, args... );
}
#endif // EVENTSTOSIGNALS_H

Trying to use main.cpp:

#include <QApplication>
#include <QComboBox>
#include <QDebug>
#include <QAbstractItemView>

#include "EventsToSignals.hpp"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QComboBox w;
    w.addItems({"a", "bb", "cccc", "ddddd"});

    connectEvent( w.view(), QEvent::Show, [](QObject /*watched*/, QEvent /*event*/){
        qDebug()<<"Show popo-up view";
    });

    w.show();
    return a.exec();
}

..\..\EventToSignal\example\../src/EventsToSignals.hpp:34:90:   required from 'auto connectEvent(QObject*, QEvent::Type, Args ...) [with Args = {qMain(int, char**)::<lambda(QObject, QEvent)>}]'
..\..\EventToSignal\example\main.cpp:16:6:   required from here
C:\Qt\5.15.2\mingw81_32\include/QtCore/qglobal.h:121:63: error: static assertion failed: Signal and slot arguments are not compatible.
 #  define Q_STATIC_ASSERT_X(Condition, Message) static_assert(bool(Condition), Message)
                                                               ^~~~~~~~~~~~~~~
C:\Qt\5.15.2\mingw81_32\include/QtCore/qobject.h:328:9: note: in expansion of macro 'Q_STATIC_ASSERT_X'
         Q_STATIC_ASSERT_X((FunctorArgumentCount >= 0),

Help please!

Christian Ehrlicher

@Alexey-Serebryakov said in Event to signal:

(QObject /watched/, QEvent /event/)

Don't know if this is thea reason but this signature is wrong. There signal does not emit objects but pointers.

Alexey Serebryakov

@Christian-Ehrlicher Oh! Sorry, my mistakes! :-) Thanks a lot.